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.TH T_RCVV 3NSL "May 7, 1998"
.SH NAME
t_rcvv \- receive data or expedited data sent over a connection and put the
data into one or more non-contiguous buffers
.SH SYNOPSIS
.LP
.nf
#include <xti.h>




\fBint\fR \fBt_rcvv\fR(\fBint\fR \fIfd\fR, \fBstruct t_iovec *\fR\fIiov\fR, \fBunsigned int\fR \fIiovcount\fR, \fBint *\fR\fIflags\fR);
.fi

.SH DESCRIPTION
.sp
.LP
This function receives either normal or expedited data.  The argument  \fIfd\fR
identifies the local transport endpoint through which data will arrive,
\fIiov\fR points to an array of buffer address/buffer size pairs
(\fIiov_base\fR, \fIiov_len\fR). The  \fBt_rcvv()\fR function receives data
into the buffers specified by  \fIiov\fR\fB0\fR\fI\&.iov_base\fR,
\fIiov\fR\fB1\fR\fI\&.iov_base\fR, through  \fIiov
[iovcount-1].iov_base\fR\fB,\fR always filling one buffer before proceeding to
the next.
.sp
.LP
Note that the limit on the total number of bytes available in all buffers
passed:
.sp
.in +2
.nf
\fIiov(0).iov_len + . . + iov(iovcount-1).iov_len)\fR
.fi
.in -2

.sp
.LP
may be constrained by implementation limits. If no other constraint applies, it
will be limited by \fBINT_MAX\fR. In practice, the availability of memory to an
application is likely to impose a lower limit on the amount of data that can be
sent or received using scatter/gather functions.
.sp
.LP
The argument iovcount contains the number of buffers which is limited to
\fBT_IOV_MAX,\fR which is an implementation-defined value  of at least 16. If
the limit is exceeded, the function will fail with \fBTBADDATA\fR.
.sp
.LP
The argument flags may be set on return from  \fBt_rcvv()\fR and specifies
optional flags as described below.
.sp
.LP
By default,  \fBt_rcvv()\fR operates in synchronous mode and will wait for data
to arrive if none is currently available. However, if  \fBO_NONBLOCK\fR is set
by means of  \fBt_open\fR(3NSL) or  \fBfcntl\fR(2), \fBt_rcvv()\fR will execute
in asynchronous mode and will fail if no data is available. See \fBTNODATA\fR
below.
.sp
.LP
On return from the call, if  \fBT_MORE\fR is set in flags, this indicates that
there is more data, and the current transport service data unit (TSDU) or
expedited transport service data unit (ETSDU) must be received in multiple
\fBt_rcvv()\fR or \fBt_rcv\fR(3NSL) calls.  In the asynchronous mode,  or under
unusual conditions (for example, the arrival of a signal or  \fBT_EXDATA\fR
event), the  \fBT_MORE\fR flag may be set on return from the  \fBt_rcvv()\fR
call even when the number of bytes received is less than the total size of all
the receive buffers.  Each  \fBt_rcvv()\fR with the  \fBT_MORE\fR flag set
indicates that another  \fBt_rcvv()\fR must follow to get more data for the
current TSDU.  The end of the TSDU is identified by the return of a
\fBt_rcvv()\fR call with the  \fBT_MORE\fR flag not set.  If the transport
provider does not support the concept of a TSDU as indicated in the  \fIinfo\fR
argument on return from  \fBt_open\fR(3NSL) or \fBt_getinfo\fR(3NSL), the
\fBT_MORE\fR flag is not meaningful and should be ignored.  If the amount of
buffer space passed in  \fIiov\fR is greater than zero on the call to
\fBt_rcvv()\fR, then \fBt_rcvv()\fR will return  \fB0\fR only if the end of a
TSDU is being returned to the user.
.sp
.LP
On return, the data is expedited if  \fBT_EXPEDITED\fR is set in flags.  If
\fBT_MORE\fR is also set, it indicates that the number of expedited bytes
exceeded nbytes, a signal has interrupted the  call, or that an entire ETSDU
was not available (only for transport protocols that support fragmentation of
ETSDUs).  The rest of the ETSDU will be returned by subsequent calls to
\fBt_rcvv()\fR which will return with  \fBT_EXPEDITED\fR set in flags. The end
of the ETSDU is identified by the return of a  \fBt_rcvv()\fR call with
\fBT_EXPEDITED\fR set and  \fBT_MORE\fR cleared.  If the entire ETSDU is not
available it is possible for normal data fragments to be returned between the
initial and final fragments of an ETSDU.
.sp
.LP
If a signal arrives, \fBt_rcvv()\fR returns, giving the user any data currently
available.  If no data is available,  \fBt_rcvv()\fR returns  -1, sets
\fBt_errno\fR to \fBTSYSERR\fR and  \fBerrno\fR to \fBEINTR\fR. If some data is
available,  \fBt_rcvv()\fR returns the number of bytes received and
\fBT_MORE\fR is set in flags.
.sp
.LP
In synchronous mode, the only way for the user to be notified of the arrival of
normal or expedited data is to issue this function or check for the
\fBT_DATA\fR \fBor\fR \fBT_EXDATA\fR events using the  \fBt_look\fR(3NSL)
function.  Additionally, the process can arrange to be notified via the EM
interface.
.SH RETURN VALUES
.sp
.LP
On successful completion,  \fBt_rcvv()\fR returns the number of bytes received.
Otherwise, it returns  -1 on failure and \fBt_errno\fR is set to indicate the
error.
.SH VALID STATES
.sp
.LP
\fBT_DATAXFER\fR, \fBT_OUTREL\fR.
.SH ERRORS
.sp
.LP
On failure,  \fBt_errno\fR is set to one of the following:
.sp
.ne 2
.na
\fB\fBTBADDATA\fR\fR
.ad
.RS 15n
\fIiovcount\fR is greater than  \fBT_IOV_MAX.\fR
.RE

.sp
.ne 2
.na
\fB\fBTBADF\fR\fR
.ad
.RS 15n
The specified file descriptor does not refer to a transport endpoint.
.RE

.sp
.ne 2
.na
\fB\fBTLOOK\fR\fR
.ad
.RS 15n
An asynchronous event has occurred on this transport endpoint and requires
immediate attention.
.RE

.sp
.ne 2
.na
\fB\fBTNODATA\fR\fR
.ad
.RS 15n
\fBO_NONBLOCK\fR was set, but no data is currently available from the transport
provider.
.RE

.sp
.ne 2
.na
\fB\fBTNOTSUPPORT\fR\fR
.ad
.RS 15n
This function is not supported by the underlying transport provider.
.RE

.sp
.ne 2
.na
\fB\fBTOUTSTATE\fR\fR
.ad
.RS 15n
The communications endpoint referenced by \fIfd\fR is not in one of the states
in which a call to this function is valid.
.RE

.sp
.ne 2
.na
\fB\fBTPROTO\fR\fR
.ad
.RS 15n
This error indicates that a communication problem has been detected between XTI
and the transport provider for which there is no other suitable XTI error
\fB(t_errno)\fR.
.RE

.sp
.ne 2
.na
\fB\fBTSYSERR\fR\fR
.ad
.RS 15n
A system error has occurred during execution of this function.
.RE

.SH TLI COMPATIBILITY
.sp
.LP
In the \fBTLI\fR interface definition, no counterpart of this routine was
defined.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7)  for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
MT Level	Safe
.TE

.SH SEE ALSO
.sp
.LP
.BR fcntl (2),
.BR t_getinfo (3NSL),
.BR t_look (3NSL),
.BR t_open (3NSL),
.BR t_rcv (3NSL),
.BR t_snd (3NSL),
.BR t_sndv (3NSL),
.BR attributes (7)
